Vulnerability to the addictive properties of alcohol and the risk for developing alcoholism appear to be influenced not only by environmental variables but also by complex genetic variations within the population. A key question in efforts to understand the vulnerability to alcohol abuse is whether increased sensitivity to alcohol is due to genetic variation in sensitivity to the central nervous system effects of ethanol. Several laboratories have demonstrated that the glutamatergic system is a target for the actions of ethanol. Mouse and rat research in alcoholism has lead to the generation of various lines of experimental animals with unique sensitivities to ethanol and other drugs of abuse. Recently, it has been shown that Drosophila can be used as a model organism for probing alcohol sensitivity and as a possible means for identifying genes that cause differential sensitivity to ethanol. We recently discovered that flies with mutations in two glutamate biosynthesis genes, glutamate dehydrogenase (GLUD) and glutamate-pyruvate transaminase (GPT), are hypersensitive to ethanol. The goal of the studies outlined in this application is to follow up on these observations and test the hypothesis that mutations or polymorphisms in primary enzymes that regulate the pools of L-glutamic acid available to serve as a neurotransmitter lead to enhanced sensitivity to the CNS actions of ethanol. In order to accomplish this goal, four objectives are paramount. Firstly, we investigate whether other previously identified Drosophila mutants of glutamate biosynthesis genes, namely glutamate-oxaloacetate transaminase (GOT1 and GOT2), and glutamine synthetase 1 (GS1), are hypersensitive to alcohol, and whether wild-type transgenes of GLUD, GPT, GOT1, GOT2, and GS1 can rescue the ethanol hypersensitivity phenotype. Secondly, we will generate knock-out alleles of other Drosophila, glutamate biosynthesis genes, i.e. glutaminase (GLUT) and glutamine synthetase2 mutant Drosophila and mouse models that are hypersensitive to ethanol have altered level or activities of several glutamate biosynthesis enzymes. Fourthly, we will generate mouse knock outs of the mouse GLUD gene and determine in these mice have a hypersensitivity to ethanol. The strength of this programmatic research approach resides in the power of the Drosophila genetic model to target specific genes that might play a role in the complex condition and ethanol hypersensitivity to ethanol. The strength of this programmatic research approach resides in the power of the Drosophila genetic model to target specific genes that might play a role in the complex condition of ethanol hypersensitivity in both Drosophila and mammalian species, including humans. This genetic approach would eventually lead to a better understanding to a better understanding of the genetic influences that underlie risk for alcoholism.